Thick and yellow tongue coating is mainly caused by internal obstruction of dampness and heat. There are two main causes of dampness and heat in the body, one is phlegm-dampness and heat, and the other is external dampness and heat. 1. Phlegm-dampness heat: patients with spleen and stomach transport function, coupled with the consumption of fat, sweet, thick and greasy food, the body will produce phlegm-dampness evil, when phlegm-dampness is not relieved for a long time, it will be rich and transformed into heat (evil too long to stay in the heat is transformed into heat) the emergence of the evil of dampness-heat, so that the patient showed the symptoms of the tongue coating and yellow and thick. 2. external dampness and heat: patients will also be due to external dampness and heat caused by tongue coating and thick and yellow symptoms, patients external dampness and heat epidemic, dampness and heat prevalence, from the surface into the inner, inner Yongzhongjiao, will cause tongue coating and thick and yellow. When the patient found his tongue thick and yellow, it is recommended to go to the hospital in time by the doctor to identify the cause, and actively carry out the treatment.